Toner image fixing device with deformable cylinder

Abstract

The present invention is intended to save warm-up time of a toner image fixing device for fixing a toner image by heating and reduce manufacturing cost of the device. Elastically-deformable heat-resistant belt is made in form of a cylinder of nickel which accommodates therein a heater lamp and a reflecting plate for concentrically transferring radiant heat from the heater lamp onto a contacting portion of the cylinder-like belt with a recording paper carrying a toner image. When the recording paper is transported along a guiding plate , the driving roller rotates the heat-resistant belt in contact with the recording paper. At this time, the rotating belt and the guide plate are pressed against each other, thereby the belt is elastically deformed in radial direction. The recording paper is transported being pressed by the belt and, thereby, the toner image is fixed onto the recording paper by heat.

We claim: 
     
       1. A toner image fixing device for fixing, by heating, a toner image developed on a sheet of recording paper, comprising a rotatable cylinder body made of heat-resistant and heat-conducting material, which has a wall elastically deformable in radial direction to form a nip having a width necessary for fixing the toner image on the recording paper;   a heater disposed in the cylinder body and a plate, partially surrounding the heater, which has a first surface, which reflects heat from the heater toward the cylinder body, and a second surface which provides support to the cylinder body; and   a paper guiding member, abutting on an external cylindrical surface of the cylinder body, to elastically deform said cylinder body in radial direction to form said nip between the paper guiding member and the cylinder body and to support a reverse side of the recording paper bearing, on its upper side, the toner image.   
     
     
       2. A toner image fixing device as defined in claim 1, wherein the paper guiding member is a flat plate supported by a heat insulating member tending to reduce heat loss from the cylinder body through the paper guiding member.   
     
     
       3. A toner image fixing device as defined in claim 1, wherein the paper guiding member is a roller. 
     
     
       4. A toner image fixing device for fixing a toner image developed on a sheet of recording paper by heating, comprising: a rotatable cylinder body made of heat-resistant and heat-conducting material, which has a wall elastically deformable in radial direction to form a nip of width necessary for fixing the toner image on the recording paper;   a heater disposed in the cylinder body;   a reflector plate abutting on an inner cylindrical surface of the cylinder body to reflect radiation heat from the heater;   a paper guiding member abutting on an external cylindrical surface of the cylinder body to elastically deform said cylinder body in radial direction to form a the necessary nip therebetween and to support a reverse side of the recording paper carrying the toner image developed on its top side;   a driving roller for rotating the cylinder body being sandwiched between the driving roller and the reflector plate; and   a cylinder guiding member disposed between the driving roller and the paper guiding member around the cylinder body to regulate rotation of the cylinder body.   
     
     
       5. A toner image fixing device as defined in claim 4, characterized in that the cylinder guiding member has a sensor for sensing a surface temperature of the cylinder body to generate a temperature detection signal for controlling electric energy to the heater. 
     
     
       6. A toner image fixing device as defined in claim 4, characterized in that the reflector plate has a form suitable to concentrically irradiate an area wherein the recording paper contacts with the cylinder body. 
     
     
       7. A toner image fixing device as defined in claim 4, characterized in that the cylinder guiding member is provided with a cleaning blade being in contact with the external cylindrical surface of the cylinder body. 
     
     
       8. A toner image fixing device as defined in claim 4, characterized in that the driving roller is formed of material for cleaning the external cylindrical surface of the cylinder body or of material impregnated with silicone oil being well-releasable from the toner to apply the silicone oil to the external cylindrical surface of the cylinder body.